


Undertale/Muddy Waters Fusion

by Tsaiko



Series: Fandom/Original World Fusions [2]
Category: Undertale (Video Game)
Genre: Alternate Universe, Alternate Universe - Fusion, Alternate Universe - Underfell (Undertale), Alternate Universe - Underswap (Undertale), Bad Puns, Boats and Ships, Explicit Language, Gen, If You Squint - Freeform, Original Universe, Pre-Relationship, Puns & Word Play, Spicyhoney - Freeform
Language: English
Status: Completed
Published: 2019-12-02
Updated: 2019-12-02
Packaged: 2021-02-26 06:21:15
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,190
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21638746
Author URL: https://archiveofourown.org/users/Tsaiko/pseuds/Tsaiko
Summary: Then there was a long bone attack pinning him to the steering house, right across his cervical vertebrae."Who are you?" It sounded like the other skeleton gargled with gravel. His teeth were pointed, and sharp. In the pale moonlight, Stretch could see a single crack in his orbital bone. "Why are you on this boat?""fuck you," Stretch replied."on edge much?" Sans appeared right at his elbow. "blue won't be happy if you dust his brother.""Thank you for the confirmation that he belongs here since it seemed he wasn't going to reply," the other skeleton said. He stepped back, and the bone attack he had disappeared in a scattering of magic. Stretch gasped for breath. His vertebrae felt bruised. "Your humor still leaves a lot to be desired.""what the fuck?" Stretch said. He looked at Sans. "who is this?""stretch, meet edge. edge, stretch."***Fusion between Undertale and my original world "Muddy Waters." Featuring Undertale, Underfell, Underswap, and boats.
Series: Fandom/Original World Fusions [2]
Series URL: https://archiveofourown.org/series/1144559
Comments: 9
Kudos: 16





	Undertale/Muddy Waters Fusion

**Author's Note:**

> What is we took various Undertale universes and put them on boats? It's the story no one asked for but I wrote anyway.

Stretch felt it the moment a stranger stepped onto the boat.

He knew his brother's step like he knew the feel of the rivers in their mountain home. Blue could be quiet when he wanted to, but even the softest step made a sound on a boat: the creak of wood, the groan of a mooring rope, the change in the sound of the current as the boat rocked. Most times his brother didn't bother. Stretch was used to the pounding cadence of Blue's feet against the deck as he rushed around to pole them quickly through the water while Stretch manned the rudder or used his oar to keep them off the rocks. And Even though they'd spent the last few months far from swift running waters, Blue still walked with the rhythm of their home. This step was different. It rolled with the movement of the boat, so light it was almost silent. The monster on deck stepped with the flow of water around them. A local then. Water the odds?

Stretch pulled his magic to him as he silently got to his feet. He wasn't a fighter Never had been. Never would be. That didn't mean he was defenseless. More than one monster had gone overboard when they failed to realize that distinction.

He was below deck, but the door to the deck was open. Usually neither he nor Blue closed it unless it was snowing, raining, or the wind was too strong. Even then, they never locked it. Why bother? No one was going to board a boat that they weren't invited on to. Or at least, no one from home would do so.

Obviously, things were a bit different this far down river. Stretch could see the stars in the sky through the doorway. A sky that wasn’t even touched by sunrise. What kind of sick, twisted person got up this early in the day? The only reason Stretch was up was because he hadn't been able to fall asleep in the first place. Too many thoughts in his brain. 

Carefully, Stretch went up the stairs to the door, making sure to step over the second step which always creaked. Nothing stirred on deck. Nothing was out of place. That didn't mean it was safe. Stretch couldn't see the back end of the boat. Someone could be there. Someone was probably there. He cautiously stepped forward.

Still nothing. Stretch was beginning to wonder if he'd imagined the change in movement. He peeked around the starboard side of the steering house. Nothing. 

Just as Stretch turned around to check the other side, the intruder struck.

Even knowing that an attack was likely, Stretch was still caught off guard. One second he was looking around the empty deck of the boat. The next second his soul was blue and he was being slammed against the steering house with gravity magic. 

Magic sparked around his hand. Before Stretch could do anything with there was someone looming over him. Another skeleton monster. Bright red eyes burned into his own. Holy shit. The monster had LV. Stretch didn't even need to check him to know that. And not a little bit of LV either. Red eyelights were a sign of dangerous amounts of LV, enough that a monster might not always be in control. Nature's warning signal.

Then there was a long bone pinning him to the steering house, right across his cervical vertebrae. Stretch couldn't breathe. He didn't need to, really, but he generally liked to. The monster in front of him shifted his weight a bit more, and the bone pressed harder against his spine. His magic fled with the added pressure. 

"Who are you?" It sounded like the other skeleton gargled with gravel. His teeth were pointed, and sharp. In the pale moonlight, Stretch could see a single crack in his orbital bone. "Why are you on this boat?"

"fuck you," Stretch replied. He could hear the sound of his bones creaking as the other monster added even more pressure. 

"on edge much?" Stretch felt the displacement of air and the sudden change in the rocking of the boat as Sans appeared right at his elbow. "blue won't be happy if you dust his brother."

"Thank you for the confirmation that he belongs here since it seemed he wasn't going to reply," the other skeleton said. He stepped back, and the bone attack he had disappeared in a scattering of magic. Stretch gasped for breath. His vertebrae felt bruised. "Your humor still leaves a lot to be desired."

"what the fuck?" Stretch said. He looked at Sans. "who is this?"

"stretch, meet edge. edge, stretch." Sans did a half-hearted gesture towards each as he said their respective names. "papyrus found blue in town. if we're going to leave we need to do it now. which means we need Stretch here in one piece to get the boat moving."

"I wasn't planning on breaking him," Edge replied. His eyes cut back to Stretch in the dark. "Your brother is the captain?"

"blue? yeah," Stretch said absently. He pushed past Edge and focused most of his attention onto Sans. Who even now was beginning to pull in some of their lines. "what is going on? why is there someone on our boat? who is he? and why are we suddenly leaving town? we just got in this afternoon."

"I am standing right here. You could ask me question directly instead of pretending like I don't exist." Edge followed behind Stretch as he walked the deck. It gave him the heebie-jeebies to have a monster with that much LV at his back.

"yeah, but i don't know you from the pond scum i scraped off the hull," Stretch replied. "at least i can trust sans's answer." He paused. "most of the time."

"your lack of trust wounds me deeply." Sans's hands were full of carefully coiled rope. Stretch took it from him automatically and hung it in its place. He usually didn't care, but Blue would have a fit if rope was left loose on the deck.

"not as deeply as my foot up your ass will. come on, sans. the sooner i get answers, the sooner i start helping."

The answer came not from Sans, but from Edge. "My brother and I are from the backwaters. We're here because Sans called in a favor." The last was said like Edge tasted something foul in his mouth. "There's trouble brewing in Gislye. Some of the more fell monsters here have you and your brother marked as easy targets. Sans and Papyrus too."

"i may be easy..." Sans said. Stretch didn't know why that caused Edge to snort, but there was definitely a story there "...but let them try to take papyrus in a fight." There was definite pride in Sans's voice when he spoke about his brother.

"I already know Papyrus can hold his own," Edge said sourly. "But the goal was to not draw attention to ourselves. If we get involved with the buns or the dogs we'll have trouble."

"you could say they'll dog us all the way to the coast so we better hop to it." Stretch laughed at Sans's joke. Edge sighed. 

"Must you?"

"good one," Stretch said to Sans, ignoring Edge. "thanks for the warning. does he need to stick around?"

"I was under the impression that you were trying to make it to the coast," Edge said. Stretch looked at him out of the corner of his eye.

"maybe."

"My brother and I know every channel between here and there. We're your best hope of actually seeing the ocean." Edge pulled a pole off of the rack.

"or we could just follow the main river until we hit saltwater?" Stretch replied, uncertainty turning the statement into a question. "it's not that hard to find. you just keep going downriver until you run out of river. again, not sure why we need you to stay."

"This is what you've decided to use your favor on?" Edge said, directing his question towards Sans.

"yep." Sans made sure to pop his "p" in the most obnoxious way possible.

"Fine. I'll get this boat to the ocean. That will be the end of our debt." Edge did not sound happy about the prospect. He turned to Stretch. "We need to back this boat out into the river. We'll turn it there and head down river."

"yeah, that ain't happening."

"Excuse me?" Edge said. He had gone very still, pole still in his hands. Stretch guessed it wasn't often that the other skeleton got told no.

"first, you don't get to tell me what to do. my brother is the captain of this boat. if you want to boss someone around, go find your own boat," Stretch said. From the way Sans's shoulders were shaking, he was doing his best not to laugh. "we will leave when Blue tells us to leave. Not before. second, we can't turn the boat once we're in the current. if you want us facing downstream, we'll need to turn it at the docks."

"If I am going to help you get this painted scow to the ocean, you need to learn to do what I say." Stretch felt a rush of indignation at their boat being referred to as a scow. "And we need to back the boat out of the dock."

"you can also want a pony, but that won't make one appear on deck for you to eat," Stretch said sourly. Sans wasn't even bothering to muffle his laughter. "this boat isn't moving unless you think you can handle it alone. and if you try, i'm shoving you overboard." 

Edge narrowed his eyes. When he spoke, his words were clipped. There was a tension in the air, the pressure of magic being gathered. Sans was still laughing so Stretch figured the situation couldn't be too dire. "You might not like me, but I assure you, I can and will move this boat. With or without you on it."

Stretch scoffed. "you can't even handle me. you think threats are going to impress me?"

"Your attitude leaves much to be desired."

"well, as far as i'm concerned, you can shove your attitude up your..."

"Brother!"

Stretch closed his teeth to hold back the rest of the words. Blue was practically running down the dock with Papyrus right behind him. He looked at Stretch, then Edge, and then Sans. "What's going on?"

"nothing," Stretch said, sullenly. "seems like we have a third for awhile. we were just have a discussion on how our boat wasn't moving until you got here, and I was telling the Edgelord here that we can't back the boat into the current."

"Don't call me that," Edge snapped. Stretch gave him a tight smile. Blue stepped from dock to boat, and was surprised as it bobbed away from him. He pinwheeled his arms until he caught his balance.

"sorry. i already started unmooring it," Sans said. 

"WHERE IS RED?" Papyrus asked. Stretch winced at the volume. Edge did not look surprised.

"He went to start getting your boat ready," Edge replied.

"better go make sure he didn't set it on fire," Sans said, under his breath. Stretch snorted. He wasn't sure if anyone else had heard Sans until Edge shifted his glare to the smaller skeleton monster. Sans ignored him in favor of teleporting onto the dock. "come on paps. these three can handle this boat, and red can help us with ours."

Papyrus hesitated. "IF EDGE SAYS YOU NEED TO TURN THE BOAT..."

"Don't worry, Papyrus. We'll get the boat turned! You can count on it," Blue said. There were practically stars in his eyes. He was already moving to the pole rack, picking the longest one up and handling it with the ease of long practice.

It looked like Papyrus was going to say something else, but Sans grabbed his brother's arm and teleported them away before he could. Edge watched them go before turning to Blue. "We need to back the boat into the main channel so we can turn it downstream."

"already told you that's not happening," Stretch said. "ordering blue to do it won't make it possible."

"My brother is right! The keel is too deep to turn in the current. We need still water in order to reorient the boat," Blue explained. Edge blinked. 

"Why didn't you say that before?" Edge asked, turning to Stretch as he spoke. He didn't sound angry. Only... confused. That was the only reason Stretch didn't snark back.

"you didn't ask. just came on board and started throwing around orders. this isn't one of your flat bottomed boats," Stretch replied. "it's designed for the wild rivers."

"Clear water." It was a statement. Stretch shrugged, neither confirming nor denying how far they had traveled from home. Instead, he eyed the distance between the stern of the boat and the dock, then between the dock across the way. "Why would anyone from the clear waters be this far down river."

"we can clear the dock," Stretch said. He deliberately ignored Edge's question. "push us a few feet away and set your pole, bro."

"O.K." Blue was already moving to do what Stretch said. Blue might be the captain of the ship, but Stretch was the navigator. He always knew how to get them out of tight spots.

If he was annoyed that Stretch avoided answering his question, Edge didn't show it. He seemed to have a more immediate concern. "What do you mean we can clear it?" Edge asked. Stretch gave him a side look as he walked past towards the bow of the boat, an oar in hand. "You think there's enough room between the two docks?"

"i don't think. i know. and yeah, we're going to turn the boat right here. we're better off leading with our bow than with our ass."

"Brother, language," Blue scolded. Stretch waved him off. 

"The boat is too long. You can't turn it here," Edge said. 

"whatever, edgelord. are you going to help or just stand there and bitch?" This time Blue just sighed. Stretch ignored him in favor of meeting Edge's gaze. Red eyes bored into his. "it'll go quicker if you help but we've managed tighter turns alone. just stay out of the way."

Stretch watched Edge go through some sort of internal struggle. He wasn't sure what Edge would decide to do. He would bet money Edge would just stand there and continue to bitch. Then the other skeleton sighed. "Don't call me that. What do you need me to do?"

"oh." That put the wary look back in Edge's eyes. Stretch took a deep breath and let it out. If the guy was going to help, there was no reason to be an asshole. "sure. follow me to the front of the boat. your pole will move it faster than my oar."

"Set!" Blue yelled as he placed his pole. His feet were braced against the deck. Stretch used the oar to push the bow away from the dock. It was so dark stars were the only difference between the water below and the sky above. Stretch had to fight a moment of vertigo when the boat started moving.

"put your pole in the water and push," Stretch instructed. He half expected Edge to balk. Instead, the skeleton monster did as he was told. "swing it out. little more. how's it going Blue?"

"We're still clear of the dock!" Blue called out. The bow swung out. It was slow going. Even without a current, the deep keel tended to resist being moved. Stretch was impressed that Edge could keep the boat steady and the movement even.

"It's going to scrape the dock," Edge said. Despite his words, he kept poling. Stretch watched the dock as it got closer.

"If my brother says we'll make it we will," Blue replied. Stretch felt a pulse of warmth in his soul. It was both heartwarming and terrifying how much faith his little bro had in him. The boat was almost at the widest part of the arc. Edge was eyeing the rapidly closing distance between the bow and the dock. 

They cleared the dock with two inches to spare. Edge let out a sound that might have been a laugh. "I owe you an apology."

"you owe me several, but we can start with you telling me i was right," Stretch replied. 

"Never mind. I don't owe you anything." The words were totally dry. Stretch found himself grinning despite himself. 

They swung around until the bow was facing toward the main river. Stretch rested a hand on the rudder to read the current. The water was still in the side channel. There was no pressure. It still felt strange. Water was never still where they were from.

Suddenly, all the lights in town flared bright in the night. There was a series of howls, a call to arms that sent chills down Stretch's spine. "time to go. go to the front and pole like there are dogs on your heels." 

Edge didn't waste time arguing. He quickly moved down the boat, barely rocking it even with the speed he was moving. Blue was already moving them forward. When Edge joined his rhythm, the boat put on a burst of speed. Stretch did his best to keep them in the middle of the channel as they raced past docks and boats

They came out of the side channel and into the river at full speed. Even with Stretch leaning hard on the rudder, the current hit them broadside. The boat wobbled precariously. Edge was braced for it, but Blue stumbled. He grabbed the smaller skeleton by the back of the shirt until he found his legs again.

Slowly, slowly the boat turned. Then suddenly, they were racing downstream. It felt like flying when they skimmed the water. Stretch grinned. Let the mud eaters try to catch them. No flat bottomed boat could keep up.

"We need to wait for Sans and Papyrus." Blue brought his pole down to drag in the water and slow them down. He didn't need to do it for long. Papyrus and Sans's boat pulled up beside them just a minute later.

"Nice boat, boss." That must be the mysterious Red. His eyes were just as red as his brother's. "Wouldn't go five feet in the back channels. It'a get stuck and picked clean in an hour."

Stretch had never seen his brother get mad, but his boat was his pride and joy. Blue turned the color of his namesake. He didn't get out any words. Edge "Enough brother. Find us a side channel big enough for the boats so we can anchor until morning. We'll have an easier time navigating in the day."

"Right, boss." 

"still don't see why we need you," Stretch replied.  
"Let's see if you still say that when morning comes," Edge said dryly. Blue gave Red one last glare before he continued poling. Stretch sighed. 

Lovely. This was going to be interesting.

**Author's Note:**

> Did I mention I stress write? And I spent Thanksgiving with my family? Have the result.


End file.
